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Discussion Starter #1
I disassembled and cleaned out my brake calipers today, and found that they were full of this gunky, snot-like stuff. Here are a few pictures:





Clearly it's been a few years since the brakes were looked at. I cleaned that stuff out and put in new brake fluid, but I don't really feel a night and day difference. The brakes still drag a little bit and the brake is reasonably stiff, although maybe it could be bled out better. It looked like this after cleaning.





Does anybody know what that gunk was?
 

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Caused by age and lack of maintenance over the bike's lifetime. Try some new seals. Karla just did her rear caliper plus fresh fluid all around.
 

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Discussion Starter #3
I was wondering if anybody knew specifically what that stuff was. Do you think it's crud that got through the brake seals and started reacting with the brake fluid? Is that what happens to brake fluid with age and heat? Did someone sneeze on the calipers before putting them in?

Funny story, this is the first time I've done work on the brakes. I thought brake fluid was supposed to be an off-brown color until I opened up a new bottle of it.
 

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Was this the bike's first brake fluid change? My clutch fluid looked like this in the reservoir, nearly like mustard on top them milky and green closer to the bottom. I was having problems shifting from N>1 and thought the clutch might not be fully disengaging.

Here's what my fluid looked like in the reservoir Vic's Bike - Why I bled my Clutch fluid
 

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Brake fluid is hygroscopic and absorbs water out of the air. My guess is it's primarily water in a brake fluid suspension as a result of the interaction between the glycol ethers in the brake fluid and moisture. Any dirt that gets past the seals could add to that.
 

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Water. Need to flush the system regularly with quality DOT4 fluid.
 

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Is this an older bike? heres why I ask....

At one point, everyone had a hard on about using dot5 fluid. Awesome, but it let moisture fall right into the caliper and looked just like yours. I wonder if someoen tried to convert your bike???
 

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Is this an older bike? heres why I ask....

At one point, everyone had a hard on about using dot5 fluid. Awesome, but it let moisture fall right into the caliper and looked just like yours. I wonder if someoen tried to convert your bike???
My bike was brand new and the fluid looked like this!
 

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Brake fluid is hygroscopic and absorbs water out of the air. My guess is it's primarily water in a brake fluid suspension as a result of the interaction between the glycol ethers in the brake fluid and moisture. Any dirt that gets past the seals could add to that.
exactly correct..in combination of the fluid breaking down but also geling up due to heat

the other possibility is someone used WAY too much assy lube at the factory
 

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exactly correct..in combination of the fluid breaking down but also geling up due to heat

the other possibility is someone used WAY too much assy lube at the factory
Unless it's one of those other "fancy" brake fluids that are silicone or mineral oil based (Dot2/3/5.1) .... I hope the PO didn't try to mix them.
 

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Discussion Starter #11
Thanks for the info guys. I've had this bike for 2 years or so, and the previous owner did some brake work before. It's a 2003. This is just the first time I've done brake maintenance.
 

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As was stated on an earlier post brake fluid is "Hygroscopic", it absorbs moisture directly from the air. That is why it goes from being a clear fluid and turns into the darker colors. There are PH test strips that are used to test the acid contamination level of the brake fluid. Those colors are caused by the contamination. Original equipment brake lines also allow this moisture to be absorbed directly through the lines. And I am assuming that they are the original lines. That makes them at least 11 to12 years old and the lines degrade rapidly with age. When water is mixed with brake fluid it forms an acid that combined with the degradation of the aluminum, steel, and rubber parts will form some nasty gunk. The only way to keep this from happening is to follow the Manufacturers Recommended Service intervals prescribed in the owners manual. Basically completely flush out and change the fluid at least every other season. Also replacing the stock lines with high quality Teflon cored braided stainless steel covered brake lines will totally undo the brake line problem and really improve brake performance and feel. Just be advised that the front brake line kits come in 2 different configurations. A "race style" 2 line kit and an "OEM style" kit 3 line kit. The 2 line kit bypasses the front pressure activated brake light switch/brake line junction with the 2 lines going from the master cylinder directly to the calipers. The 3 line kit routes as did the original lines using the line junction/switch as do the stock units. I bought mine through ebay from a motorcycle parts and accessory supplier and are Galfer Brand kits. I bought kits for both the front and rear brakes. I have made this modification on every motorcycle and car I've have owned and/or raced since the early 70's and highly recommend this to everyone. Basically water intrusion and contamination is almost the sole cause of internal brake components wear and failure. I have done literally thousands of partial and complete brake jobs and know this to be totally true. Also NEVER NEVER NEVER use a "higher grade" brake fluid than is specified by your manufacturer in the owners manual. Individual brake components may not be compatible with the different than OEM style fluids. Catastrophic brake failure could result. I can't stress this point enough. (Oh and Clean new brake fluid IS what is used as an assembly lube at the factory)
 
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